Regional modeling of dust mass balance and radiative forcing over East Asia using WRF-Chem

Abstract

The Weather Research and Forecasting model with Chemistry (WRF-Chem) is used to investigate the seasonal and inter-annual variations of mineral dust over East Asia during 2007-2011, with a focus on the dust mass balance and its direct radiative forcing. A variety of in situ measurements and satellite observations have been used to evaluate the simulation results. Generally, WRF-Chem reasonably reproduces not only the column variability but also the vertical profile and size distribution of mineral dust over and near the dust source regions. In addition, the dust lifecycle and processes that control the seasonal and spatial variations of dust mass balance are investigated over seven sub-regions of desert dust sources (Taklimakan Desert (TD) and Gobi Desert (GD)), the Tibetan Plateau (TP), Northern China, Southern China, the ocean outflow region, and Korea-Japan. Over the two major dust source regions of East Asia (TD and GD), transport and dry deposition are the two dominant sinks with contributing of ~25% and ~36%, respectively. Dust direct radiative forcing in a surface cooling of up to -14 and -10Wm-2, atmospheric warming of up to 9 and 2Wm-2, and TOA (Top of atmospheric) cooling of -5 and -8Wm-2, respectively. Dust transported from the TD is the dominant dust source over the TP with a peak in summer. Over the identified outflow regions (the ocean outflow region, and Korea-Japan), maximum dust column concentration in spring is contributed by transport. Dry and wet depositions are comparable dominant sinks, but wet deposition is larger than dry deposition over the Korea-Japan region, particularly in spring (70% versus 30%). The ability of WRF-Chem to capture the measured features of dust optical and radiative properties and dust mass balance over East Asian provides confidence for future investigation of East Asia dust impact on regional or global climate.